Force-resisting devices and methods for structures

ABSTRACT

In accordance with the present invention there is provided a force-resisting device for transmitting forces and dissipating and absorbing energy across a discontinuous structural element of a structure. The device includes at least one active element, the active element having defined force versus deflection properties and able to transmit force and dissipate and absorb energy, one end of the active element configured to be connected to a structure, and at least one frame element disposed about a discontinuous structural element, wherein the frame is configured to be connected to a second end of the active element, wherein the active element and the frame element configured to resist forces applied to the structure by transmitting forces across the discontinuous structural element.

1. FIELD OF THE INVENTION

[0001] The present invention relates to devices and methods fortransmitting forces and dissipating and absorbing energy acrossdiscontinuous structural elements. More particularly, the presentinvention relates to a force-resisting device for transmitting forcesand dissipating and absorbing energy. The device includes at least oneactive element; the active element configured to effect thetransmission, dissipation, and absorption functions by means ofcontrolled deformation.

2. BACKGROUND OF THE INVENTION

[0002] Building structures must be designed to safely withstand forcesthat may be applied thereto. As construction techniques improve,buildings are more capable of resisting loads that are applied thereto.Examples of loads that may be applied to buildings are those that resultfrom earthquakes and windstorms. These forces may resolve within astructure as tension, compression, shear, torsion, or bending forces. Ofthe forces produced by such events on a building, horizontal (or shear)loads are significant. These horizontal forces attempt to shear (slide)the building off its foundation. Additionally, horizontal forces thatdevelop in an upper story of a multiple story structure are transmittedto the lowest story primarily as in-plane shear loads on the lower storywalls. In conjunction with shear forces, “uplift” or “overturning”forces also result on the structure. These uplift/overturning forces,generated in reaction to the moment of the shear force, attempt to liftand rotate the walls of the structure about a lower corner of the wall.In fabricating the structure, the structure must be designed withsufficient “shear resistance” so that the structure does not sustainexcessive non-structural and/or structural damage or collapse due toapplied forces, potentially resulting in extensive economic cost,serious injury or loss of life. Shear resistance can be further definedas the ability of a structure to absorb, dissipate, and transfer forces.To address the need to build a structure having sufficient strength,uniform building codes (“UBC's”) provide required building practiceswherein the prescribed goal is life safety, but not necessarily toretain the building as habitable after a natural disaster.

[0003] Damage caused by forces resulting from seismic and hurricaneevents has exposed the need for improved force-resisting structuresand/or structural elements for both new building structures and forretrofit into existing building structures.

[0004] Prior to the creation of the UBC's, early buildings wereconstructed having little or no capability to resist shear forces,uplift from foundations, and other loads. Walls of the structure weregenerally constructed only of vertical frame members with horizontalplanks nailed across them. Later improvements included the use ofdiagonal wood braces, or diagonal sub-planking in the walls, with eithershingles or some other outer layer to exclude weather and provide afinished exterior. However, as understanding of building performance inearthquakes and hurricanes continues to improve, the necessity forbetter structural properties has become more apparent and is beingmandated by the UBC.

[0005] In general construction, the most common way of producing a shearwall is to use plywood sheathing attached to a plurality of vertical 2×4or 2×6 inch wooden or metal framing members. The plywood sheathing isattached to the framing members with closely spaced nails/screws on theedges of the plywood panel. The use of the plywood sheathing andspecified fastening patterns that are incorporated into all modernbuilding codes has proven to be a very successful method of producing awall having shear resistance. Analysis of damage caused in recentearthquakes, such as the 1994 Northridge earthquake in California,illustrated that in some cases, buildings built to the standardsspecified in the California UBC survived rather well. However, therewere a substantial number of structural failures generally associatedwith openings formed in shear walls and stress concentrations onsteel-frame building connections. Although, a building may remainstanding after an earthquake, it still may be rendered uninhabitable dueto non-structural and/or structural damage.

[0006] Problems caused by openings are twofold: stiffness reduction andstress concentrations. First, openings dramatically reduce the shearstiffness of the wall. For example, even comparatively small windowopenings will reduce the shear stiffness sufficiently that the wall canno longer be considered a continuous shear wall, thereby increasing theeffective aspect ratio of the wall, wherein the aspect ratio is definedas the ratio of the height of the wall H to the width of the wall W.When the aspect ratio of the wall is increased, the overturning forceson the wall for the constant overturning moment (where the moment isdetermined by story height and shear force only) become higher and morelocalized.

[0007] Referring now to FIG. 1, there is illustrated an exemplaryembodiment of an isolated shear wall 10 illustrating the balance offorces applied thereto. The force F is the shear force carried by theshear wall at the top edge due to a loading event such as an earthquake.The force must be reacted in shear at the foundation, shown by theopposing force F at the bottom. The moment of F relative to thefoundation, equal to F multiplied by the story height H, must be reactedby foundation vertical or overturning forces A1, A2 (shown as discrete,but may be distributed near the corners). The force A2 is particularlytroublesome, as it is tensile against the foundation, and is equal to(H/W)×F. In a case where there are adjacent additional structures, someof the overturning moment may be carried by shear on the sides of theshear wall 10, but eventually the entire overturning moment must bereacted at the foundation by vertical forces, and those forces areproportional to the panel aspect ratio H/W.

[0008] Referring now to FIG. 2A, there is shown an exemplary embodimentof a shear wall 10 wherein an opening O has been formed within the shearwall. As shown in FIG. 2A, the opening creates a discontinuity in theforce transmitting characteristics of the shear wall, wherein forcesthat are normally carried across the entire wall width W now must becarried across the reduced width W′. The reduced width is less stiff andless strong, and the opening corners also introduce panel stressconcentrations that did not previously exist. The corners A tend tocrack open, and the corners B tend to crush and buckle closed, under thedirection of force F′ shown, as FIG. 2B shows. Therefore, the loadcarrying stiffness and overall strength of this shear wall issubstantially reduced. In addition, if adjacent structures exist, theywill be caused to carry more forces because this panel is less stiff andas a result takes up a smaller proportion of the forces.

[0009] To address the weakness created in shear walls due to openingsformed therein, there have been recent changes in the UBC. The recentchanges to the UBC have halved the maximum aspect ratio of shear wallsand shear wall segments so that the minimum width of an 8 ft high shearwall has been increased from 2 ft. to 4 ft, for a maximum aspect ratioof two.

[0010] Another problematic variable in the construction of a building isthe variations in construction quality, foundation quality, and soilvariability. Following the 1994 Northridge earthquake, it was discoveredthat a large percentage of building failures occurred as a result ofpoor field construction practice. One study indicated that one third ofthe seismic safety items installed were missing and/or improperlyinstalled or poorly implemented in over 40% of the structures surveyed.

[0011] Further still, it is important that structural elements withinthe building structure have generally similar strength and stiffnessproperties in order to share the applied loads. If every structuralelement does not work together, this may lead to excessive damage orfailure of a structural element due to force over-loading of thestructural element, as opposed to load sharing. There may be locationswithin a building structure wherein walls having differentstiffness/strength are joined together. For example, a structure may bebuilt with a concrete retaining wall, wherein timber-framed shear wallsmay be joined to the poured concrete retaining wall. Many times, duringseismic events the connection point of the two walls having differentstiffness will separate due to the difference in stiffness of the wallsin relation to the movement of the wall in response to the seismicevent. In addition, irregular placement of structural elements withvarying stiffness/strength characteristics can result in twisting of thestructure leading to additional torsional stresses and other stressamplifications. Thus, there is a need for a device that will transmitforces and dissipate and absorb energy across discontinuous structuralelements.

[0012] In addition to that above, another aspect to be considered is themanner in which the UBC is interpreted by local building inspectors.Often, building inspectors will make highly restrictive interpretationsof the building codes in an effort to promote increased safety inbuilding practices.

[0013] There have been numerous attempts to address increasing the shearresistance of a structure where the structure includes a number ofdiscontinuities/openings formed in shear wall(s). One of the most commonmethods of addressing the need to increase the shear resistance of astructure has been to include a moment frame in the design of thestructure, whereby steel beams are rigidly connected together such thatany force applied to the structure will be carried through the momentframe. A moment frame is typically embodied as a large heavy steelstructure designed to transmit shear forces of the structure into thefoundation or into special footings formed in the foundation, viabending (or moment) resistance of large steel members. However, a momentframe must be specifically engineered for each application, thus addingsignificant cost and complexity to the structure. In residentialconstruction, even a modest opening in a shear wall can require 6″ or 8″steel girders weighing hundreds of pounds and the attendant foundationreinforcement required to absorb the loads transmitted thereto by themoment frame. The architect/builder must also account for shipping andhandling costs associated with the installation of these heavy steelbeams on the building site. Further still, the use of a moment framecauses significant problems with the insulating properties of thebuilding, as the metal beams act to conduct heat through the walls ofthe structure to the interior of the structure, thus causing degradationof insulation properties.

[0014] Although moment frames appear to be a solution, albeitinefficient, to increase the shear resistance of a structure, there arestill shortcomings of the popular field welded-field boltedbeam-to-column moment frame connection. Observation of damage sustainedin buildings during the 1994 Northridge earthquake showed that, at manysites, brittle fractures occurred within the connections at very lowlevels of loading, even while the structure itself remained essentiallyelastic (Federal Emergency Management Administration Report 350). Thistype of connection is now not to be used in the construction of newseismic moment frames. For example, tests conducted by the SeismicStructural Design Associates, Inc. (SSDA) have shown large stress andstrain gradients in moment frame joints/connections that exacerbatefracture. To address these large concentrations of stress in thecorners, there has been much work attempting to improve the ability ofthe corners of a moment frame to resist loads. One such improvement to acorner connection is embodied in U.S. Pat. No. 6,237,303.

[0015] Another approach to structural reinforcement is to utilize apre-built shear wall such as the Simpson StrongWall®. The StrongWall® isa pre-built shear wall that may be integrated into a building structure.The StrongWall® is constructed of standard framing materials and metalconnectors. The StrongWall® further includes a plurality of devicesconfigured to anchor the StrongWall® to a building foundation. TheStrongWall® must be connected to the framing of the structure as well asto the foundation. Because the StrongWall® must be connected to thestructure's foundation, this requires special work on the foundationprior to installation, thus rendering retrofit application of theStrongWall® not cost effective. In addition, the StrongWall® isdelivered to a job site as a pre-built panel, thus the architect/buildermust account for shipping and handling costs associated with theinstallation of these heavy panels on the building site.

[0016] Shortcomings of both moment frames and StrongWalls® are that bothdevices do not attempt to match the shear stiffness and strengthcharacteristics of the surrounding structure. Instead, each device isdesigned without regard for the structure it will be used within, and isgenerally designed to carry the entire shear load of a wall or wallsegment. As described above, a moment frame is typically constructed ofsteel beams, wherein the beams are rigidly connected together such thatany force applied to the structure will be carried through the momentframe and into the foundation. The StrongWall® is designed in a similarmanner, wherein the StrongWall® attempts to be stronger than thesurrounding structure. Moment frames and larger StrongWalls®, due totheir size and weight, can be difficult to move around the job site andinstall without the use of costly heavy equipment. Both the moment frameand the StrongWall® significantly increase the overall cost of thestructure. Therefore there is a need for a lightweight device that maybe installed within or about openings of a structure to maintain theproperties of that structure as a generally continuous element.

[0017] While the two devices described above may be readily utilized innew construction there is still a need for devices that may be utilizedduring structural retrofits, seismic or hurricane upgrades, and/orremodels. For example, a homeowner may cut an opening in a shear wall toplace a new window or doorway. Many times, these home retrofits are donewithout any consideration to shear strength of the wall or obtaining apermit. Thus, when the homeowner wishes to sell their house thatincludes these “improvements”, many times their homes will not meet codeand cannot be sold as is. What is therefore needed is a device that canbe readily adapted to retrofits to maintain the properties of thestructure as a generally continuous element after an opening has beenformed in the shear wall. There is also a need for an easilymanufactured, lighter, less complicated, more versatile, adjustable,easier to install device for new construction.

SUMMARY OF THE INVENTION

[0018] The purpose of the present invention is to provide devices andmethods for structurally reinforcing a building element such as a shearwall, while eliminating the high cost, complexity, weight and handlingproblems of the prior art, while further allowing a builder and/orarchitect to consider the entire wall as a generally continuous shearwall, and to allow a structure to be designed without having to considerany of the discontinuity problems previously described. A furtherpurpose is to eliminate the need to repeatedly engineer solutionsspecific to particular shear-resisting elements, openings anddiscontinuities in specific buildings, and to allow the safeinstallation of windows and doors in existing buildings without the needfor extensive design, structural reinforcement or engineeredmodifications.

[0019] To accomplish these purposes there is provided a force-resistingdevice for transmitting forces and dissipating and absorbing energyacross a discontinuous structural element of a structure. The deviceincludes at least one active element, the active element having definedforce versus deflection properties, wherein the active element isconfigured to provide a load path across a discontinuous structuralelement.

[0020] In one embodiment there is provided another force-resistingdevice for transmitting forces and dissipating and absorbing energyacross a discontinuous structural element of a structure, the deviceincluding at least one active element having at least a first end and asecond end, the active element having defined force versus deflectionproperties and configured to transmit force and dissipate and absorbenergy, wherein the first end of the active element is configured to beconnected to a structure; and at least one frame element disposed abouta discontinuous structural element, wherein the frame element isconfigured to be connected to the second end of the active element, theactive element and the frame element configured to resist forces andreduce stresses and replace stiffness, dissipation, and strength to thestructure.

[0021] In a further embodiment there is provided yet anotherforce-resisting device for transmitting forces and dissipating andabsorbing energy across a discontinuous structural element of astructure, the device including at least one active element having atleast a first end and a second end, the active element having definedforce versus deflection properties and configured to transmit force anddissipate and absorb energy, wherein the first end of the active elementis configured to be connected to a structure. The force-resisting devicefurther includes at least one frame element configured to be connectedto a discontinuous structural element, the frame element is configuredto be connected to the second end of the active element, wherein theactive element and the frame element configured to resist forces appliedto the structure by transmitting forces across the discontinuousstructural element.

[0022] In a further embodiment there is provided yet anotherforce-resisting device for transmitting forces and dissipating andabsorbing energy across a discontinuous structural element of astructure, the device including at least one active element having atleast a first end and a second end, the active element having definedforce versus deflection properties and configured to transmit force anddissipate and absorb energy, wherein the first end of the active elementis configured to be connected to a structure, and at least onereinforcement element, the reinforcement element configured to beconnected to a structure. The force-resisting device further includes atleast one frame element configured to be disposed about a discontinuousstructural element, wherein the frame element is configured to beconnected to the second end of the active element, the active element,the frame element, and the reinforcement element configured to resistforces applied to the structure by transmitting forces across thediscontinuous structural element and further configured to reducestresses and replace stiffness, dissipation, and strength to thestructure.

[0023] In still another embodiment there is provided a method ofrestoring the stiffness, energy dissipation capacity, and strength of astructure containing a discontinuous structural element, the methodincluding the step of: transmitting forces across the discontinuousstructural element, thereby providing load sharing across thediscontinuity.

[0024] In a further embodiment there is provided a method for selectinga force-resisting device, the device configured to transmit loads and todissipate and absorb energy, the method including the steps of;selecting a structural element to be reinforced; selecting a designconfiguration of a force-resisting device containing at least one activeelement; selecting a design configuration for the active element;building a computer generated finite element model of theforce-resisting device with at least one degree of freedom fortransmitting force and dissipating and absorbing energy; and using thecomputer generated finite element model in a finite element analysisprogram to iterate the design of the active element to produce definedforce versus deflection properties.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] Features and advantages will become apparent from the followingand more particular description of the preferred embodiments of theinvention, as illustrated in the accompanying drawings, and in whichlike reference numerals generally refer to the same parts or elementsthrough-out the view, and in which:

[0026]FIG. 1 is an elevational view of an exemplary shear wallillustrating the balance of forces applied thereto;

[0027]FIG. 2A is an elevational view of an exemplary shear wallincluding an opening formed therein illustrating the reduction of loadbearing width;

[0028]FIG. 2B is an elevational view of an exemplary shear wallincluding an opening formed therein illustrating the concentration ofstresses in the corners of the opening;

[0029]FIG. 3 is an elevational view of the backside of an exemplaryshear wall illustrating the stud framing and sheathing attached thereto;

[0030]FIG. 4A is an elevational view of an exemplary embodiment of theforce-resisting device in accordance with the present invention;

[0031]FIG. 4B is an elevational view of an exemplary embodiment of theforce-resisting device according to the present invention;

[0032]FIG. 5 is a sectional perspective view of an exemplary embodimentof a force-resisting member of the force-resisting device, taken aboutline A-A of FIG. 4B, which contains an active element according to thepresent invention;

[0033]FIG. 6 is an exaggerated deformation and color-coded sheathingshear stress display of a computer simulation of an exemplary shear wallundergoing deflection due to a shear force applied thereto;

[0034]FIG. 7 is an exaggerated deformation and color coded sheathingshear stress display of a computer simulation of an exemplary shear wallhaving an opening formed therein, wherein the shear wall is undergoingdeflection due to a shear force applied thereto;

[0035]FIG. 8 is a display of a computer model of an exemplary shear wallillustrating schematically the force-resisting device according to thepresent invention as disposed about the periphery of an opening formedwithin the shear wall;

[0036]FIG. 9 is an exaggerated deformation and color-coded sheathingshear stress display of an exemplary shear wall having an opening formedtherein and the force-resisting device disposed thereabout, wherein theshear wall is undergoing deformation due to an applied force;

[0037]FIG. 10 is a graph illustrating the shear load versus deflectionproperties of an exemplary shear wall, an exemplary shear wall having anopening, and an exemplary shear wall including the force-resistingdevice according to the present invention;

[0038]FIG. 11 is a sectional perspective view of a computer model of aportion of an exemplary embodiment of a force-resisting member of theforce-resisting device, taken about line A-A of FIG. 4B, including anactive element according to the present invention;

[0039]FIG. 12 is a true scale deformation and color coded stress displayof a computer simulation of an exemplary embodiment of a force-resistingmember of the force-resisting device including the active elementundergoing progressively plastic compression due to an applied force;and

[0040]FIG. 13 is a true scale deformation and color-coded stress displayof a computer simulation of an exemplary embodiment of a force-resistingmember of the force-resisting device including the active elementundergoing progressively plastic deformation in tension.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] Definitions

[0042] As used herein the following terms are to be understood to bedefined as described below. “Load sharing” shall be understood to definethe carrying of a total load by some division among more than oneload-bearing element. For example, parallel load bearing elements carryload in proportion to their stiffness, while series load bearingelements carry full load (i.e., do not share load).

[0043] “Transmit” shall be understood to define the capacity of anelement to withstand applied forces and to react them from one locationto another, according to the laws of mechanics, specifically forceequilibrium. Transmission of forces of an element within a system alwaysdepends on its geometric configuration and its strength capacityrelative to the force magnitude to be transmitted, and in some instanceson its stiffness.

[0044] “Load path” shall be understood to define a route for load to betransmitted. “Dissipation” shall be understood to define a process ofconversion of energy from an undesirable motion form permanently andirreversibly to a benign form, which as one example involves convertingmechanical work energy (force acting over a distance) into plasticstrain energy of a material, and subsequently heat energy. Dissipationis effected by mechanical damping and plasticity, and can be used toreduce maximum deflection of structures subjected to external forces.

[0045] “Absorption” shall be understood to define a process ofconversion of energy from an undesirable motion form reversibly andtemporarily to a benign form, which as one example involves convertingmechanical work energy (force acting over a distance) into elasticstrain energy of a material, which can be later restored. Suchabsorption is effected by mechanical stiffness or springs, and can beused to reduce maximum deflection of structures subjected to externalforces.

[0046] “Force resisting” shall be understood to define the ability of adevice to transmit structural forces, to dissipate energy by some means,and to absorb energy by some means, in some absolute magnitude andrelative proportion.

[0047] “Shear wall” shall be understood to define a structure capable ofresisting shear forces, the shear wall being constructed of framingmembers having a sheathing material disposed thereon. The framingmembers may be constructed of wood, metal or similar materials.

[0048] “Active element” shall be understood to define a load-bearingelement with defined load versus deflection properties that may bedesigned by engineering analysis in one or more directions or degrees offreedom. The active element is a device configured to deflect or distortin a controlled manner under load.

[0049] “Finite element analysis” shall be understood to include the useof a computer model based on the finite element mathematical method topredict reaction forces, deformations, stresses, and strains of astructure in response to applied forces or enforced displacements.

[0050] “Discontinuous structural element” is herein defined as any loadbearing structure or portion of load bearing structure that has somefeature within it that makes the structure's force transmitting,stiffness (absorbing), dissipating, absorbing, or strengthcharacteristics non-uniform, and results in a change of load sharingwithin the structure, influences the proportion of load shared by thestructure relative to adjacent structures, or causes stressconcentrations in the structure. Examples of features that causediscontinuous structural elements are door and window openings,localized overly stiffened structural elements, coupled structuralelements with different stiffness properties, asymmetrical buildingconfigurations, locations in a structure where relative movement ofadjacent parts may occur during a loading event, or other similarfeatures.

[0051] “Generally continuous shear wall” shall be defined as a shearwall that behaves substantially the same as a continuous shear wall atits edges, i.e. load versus deflection, stiffness, and dissipationcharacteristics are similar, despite the presence of discontinuitieswithin it.

[0052] “Drift” shall be understood to define the amount of deflection ormovement of a shear wall or structural element due to a load appliedthereto.

[0053] “Retrofit” shall be understood to include remodeling,reconstruction, structural upgrading, strengthening, fabrication ofshear walls, or similar constructions processes.

[0054] The present invention provides devices and methods formaintaining the strength, stiffness (absorption), and dissipationproperties of a structure, wherein said properties have been lost due toan opening or other discontinuity formed within the structure. In thecase of an opening, the force-resisting device of the inventiontransmits the forces and dissipates and absorbs energy at the edge ofthe opening in such a manner that the exterior edges of the structureinto which the opening is cut behave under shear load substantially asif there were no opening formed in the structure. As utilized herein, itshall be understood that the term structure is intended to refer to theentire building structure or to a portion of the entire buildingstructure, such as a shear wall.

[0055] The device in accordance with one exemplary embodiment includes alightweight force transmitting and energy dissipating and absorbingforce-resisting device that may be disposed about an opening formed in ashear wall. The force-resisting device contains active elements thathave defined force versus deflection properties, which may be designedby engineering analysis, such that the forces developed about theopening due to shear on the wall are transmitted around the opening. Bydesigning the proper force-resisting device and active elements, thestress concentrations at the periphery of the opening are mitigated sothat the strength of the structure is substantially the same as if anopening had not been formed within the wall, thereby enabling a shearwall having an opening formed therein to behave as a generallycontinuous shear wall.

[0056] Referring now to FIG. 3, there is shown a shear wall 10. Theshear wall 10 as shown FIG. 3 includes, a four-foot by eight-footplywood sheathing panel 12, and a plurality of two inch by four-inchstuds 14 disposed about the periphery of the panel. The shear wall 10 asshown in FIG. 3 mimics a typically constructed shear wall in a structuresuch as a private home. It shall be understood that the shear wall 10illustrated in FIG. 3 shall be understood as being exemplary; the shearwall may be constructed of metal framing having a plywood panel disposedthereon. Furthermore, it is contemplated that other engineered materialsmay be utilized for both the framing elements as well as the sheathingmaterial.

[0057] Referring now to FIG. 4A there is shown an exemplary embodimentof the force-resisting device 100 in accordance with the presentinvention. As shown in FIG. 4A, the force-resisting device 100 includesan active element 130 disposed within a force-resisting member 120. Theforce-resisting member 120 may further include a plurality of apertures129 disposed adjacent to the active element 130, wherein the aperturesare configured to receive connection means for connecting the activeelement to a structure. Still further, the force-resisting device mayinclude a frame element 90, wherein the frame element 90 may be coupledto the force-resisting member 120. As shown in FIG. 4A, the activeelement has defined force versus deflection properties, wherein theactive element is configured to provide a load path across adiscontinuous structural element.

[0058] Referring now to FIG. 4B, there is shown an alternative exemplaryembodiment of the force-resisting device 100 in accordance with thepresent invention. As shown in FIG. 4B, the force-resisting deviceincludes at least one active element 130; the active element disposedwithin a force-resisting member 120, at least one frame element 90, andat least one reinforcement element 110. As shown in FIG. 4B, theforce-resisting device 100 is shown as being configured to be disposedabout a discontinuous structure, such as an opening formed in astructure. It shall be understood that the reinforcement element 110 maybe fixedly attached to the opening periphery utilizing suitable knownmeans such as screws, bolts, glues, or nails. Additionally, thereinforcement element 110 may be fixedly connected to an end of theforce-resisting members 120 through the use of fastening means such asthose above. Further still, it is contemplated that the reinforcementelement 110 and the force-resisting member 120 may be formed as aunitary member. It is also contemplated that the reinforcement element110 and the force-resisting member 120 may not be connected directly,but may be individually connected to the shear wall adjacent to theopening, or to some intermediate members, or to a mounting framedisposed about the periphery of the opening. The force-resisting device100 as shown in FIG. 4B and described above is shown as being configuredto be disposed about an opening, therefore the force-resisting deviceincludes at least four force-resisting members 120 and at least fourreinforcement elements 110. Additionally, as shown in FIG. 4B, the frameelements 90 are configured to be disposed about the periphery of theopening thereby forming a frame 99. The force-resisting members 120and/or the reinforcement elements 110 are attached at one side, to theopening periphery either directly or indirectly, and at the other sideto the frame 99 or a structure disposed about the opening, so thatforces can be transmitted across the opening.

[0059] Frame elements 90 or frame 99 may be configured having a varietyof structural properties. For example, the frame 99 or the frameelements 90 may be made sufficiently rigid such that any forces appliedto the frame will be transmitted with little deflection. Alternatively,the frame 99 may be configured to be “soft” or flexible, thus, the frame99 can be configured to function as an additional active element inconjunction with the other active element(s) embodied in theforce-resisting device 100 in accordance with the present invention. Itis further contemplated that the geometry of the frame 99 may beadjusted such that the frame 99 includes a plurality of active elementsformed therein. For example, the frame may be constructed includingmultiple “active folds.” It shall be understood that the reference toactive folds above should not be considered limiting and that othergeometries and embodiments of the active element as described herein maybe embodied in the frame 99 or frame elements 90.

[0060] The frame 99 may be further configured to include mountingarea(s) to receive and retain elements, such as windows and doors. Theframe 99 may be configured to receive windows or doors in differentmanners. For example, the mounting area may include a soft and resilientinterface to allow the force-resisting device, including window ordoorframe, to flex as needed, and allow the window or door to floatwithin the frame. Second, the mounting frame may be rigid, to keepdeflections so low that the window or door are not loaded even iffixedly connected to the frame, while the active element(s) sustains allthe deflection. Still further, these mounting areas can be used toprovide accurate openings into which the doors and windows could befitted without the conventional use of shims, thus cutting downinstallation time and adjustment and reducing the risk of distortion ofwindow and door frames by improper installation or subsequent settlingof the building. This aspect of the invention is especially valuable inthe case of vinyl-framed doors and windows, which are comparativelysoft, and easily distort. Incorporating a mounting frame within theforce-resisting device 100 provides an additional benefit of reducingair gaps around the window or door openings that may lead to energyloss. Yet another benefit of forming a door or window frame within theforce-resisting device 100 is that this not only provides the advantagespreviously mentioned, but also distributes any loads from attemptedforced entry directly into the structure of the wall containing theopening, thus providing greatly enhanced security for openings, asopposed to conventional door/window frames, which are simply nailed intothe rough framing of the building. An additional safety function is alsointroduced by providing a proper mounting for doors and windows,therefore the likelihood of a window shattering or a door becoming stuckor jammed due to forces applied during an earthquake is reduced becausethe device according to the present invention transmits force about theopening thereby reducing the amount of force applied to the windowpanesand/or door.

[0061] The function of the invention may be achieved with less hardwarethan shown in the exemplary embodiments of FIGS. 4A and 4B. It iscontemplated that the force-resisting device according to the presentinvention may function with a single active element, provided the activeelement is attached at a first end to the opening periphery and at asecond end to some structure that reacts the forces transmitted throughthe active element to some other location about the opening. Forexample, the device of FIG. 4B could be reduced to a singleforce-resisting member at the left side which is attached at one end tothe left side of the opening and at the other end to an “L” shaped framealong the left and top of the opening, which is in turn rigidly fixed bysome means to the opening periphery along the top. In this case, load istransmitted from the left side of the opening, through the activeelement, through the frame, to the top edge of the opening (not througha second active element). However, for best load distribution, stresscontrol, and simplicity, symmetrical configurations using two opposingor all four opening sides of a rectangular opening (or configuredsimilarly about a non-rectangular opening) are preferred.

[0062] The reinforcement element 110 and the force-resisting member 120as shown in FIGS. 4A and 4B may be constructed of materials such assteel, stainless steel, aluminum, copper, brass, titanium, or othermetals. It is further contemplated that the reinforcement element 110and the force-resisting member 120 may be constructed of engineeredcomposite materials such as fiberglass, carbon fiber, graphite,Spectra®, or similar composite materials. Still further, it iscontemplated that the reinforcement element and the force-resistingmember may be constructed of a combination of any of the materialslisted above and other materials not listed. It shall be understood thatthe list of materials above is merely exemplary and should not beconsidered limiting in any manner; it is contemplated that othermaterials not listed may be utilized in the construction of thereinforcement element or the force-resisting member in accordance withthe present invention.

[0063] Although the force-resisting device 100 is illustrated in FIG. 4Bas being formed of multiple reinforcement elements and force-resistingmembers, which are then assembled, it is contemplated that theforce-resisting device according to the present invention may beconstructed as a unitary member. Furthermore, although the presentinvention has been illustrated as being disposed about a window openingformed within a shear wall, it is contemplated that the force-resistingdevice 100 according to the present invention may be utilized around anytype of opening or structural discontinuity. For example, in a door orhallway opening where there is no remaining shear panel along the loweredge of the opening, loads may be transferred across the bottom of theopening through the use of a structural sill plate or by utilizing anexisting sill plate, if the existing sill plate is capable oftransmitting the applied loads. In some cases, with proper design of theside and top of the force-resisting device, it will also be feasible toeliminate the bottom element altogether. Further still, if thefoundation has mechanical properties sufficient to carry the appropriateforces, the vertical elements of the force-resisting device 100 may beattached to the foundation.

[0064] Referring now to FIG. 5 there is shown a sectional perspectiveview of an exemplary embodiment of the force-resisting member 120 inaccordance with the present invention. As shown in FIG. 5,force-resisting member 120 includes the active element 130 formed withinan elongated member 122, the elongated member 122 having a first end123, a second end 124, the active element 130 having defined forceversus deflection properties in the X and Y directions, such that theactive element is configured to provide load sharing across adiscontinuous structural element. The active element 130 as shown inFIG. 5 is shown as being embodied as an “active fold” formed within theelongated member 122 and disposed between the first end 123 and thesecond end 124, and formed between the edges of the elongated member122. As shown in FIG. 5, the first surface 125 and second surface 126adjacent to either side of the active element 130 are substantiallyparallel to each other, but they need not be. Further still, it iscontemplated that the force-resisting member 120 may further includeapertures 129 disposed through the substantially horizontal portions 128of the elongated member adjacent to the active element 130.

[0065] Although the active element is described and shown as being an“active fold” it is contemplated that other geometries and mechanicalstructures could be utilized. For example, the active element maycomprise any one of the following devices individually or in anycombination thereof. Examples of such active elements are: at least onecutout, a single slot, a plurality of slots (where in all cases theremaining material is the active element), a plurality of folds, aplurality of pins and engaging members (where the pins or engagingmembers deflect/distort), or an aperture having a web disposedthereacross (where the web deflects/distorts). It shall be furtherunderstood that the examples above are merely exemplary and should notbe considered limiting in any manner. Any geometry and combination(s) ofmaterials can be used for the active element that generates a usefulforce versus deflection property when loaded in one or more directions.

[0066] The active element 130 may be formed within the elongated member122 utilizing known manufacturing processes such as pressing, bending,casting, cutting, or other methods suitable for the material used. Theforce-resisting member 120 and active element 130 in accordance with thepresent invention may be constructed of materials such as those listedabove with regard to the reinforcement element 110, or combinations ofmore than one material. Under certain conditions, it may desirable tofurther tune the force versus deflection properties of the activeelement 130. The force versus deflection properties of the activeelement 130 can be tuned by increasing/decreasing the height of theactive element, providing multiple active elements within the elongatedmember 122, adjusting the geometry of the active element(s), varying thematerial thickness of the active element and/or of the elongated member122, or other variations. For example, it may be desirable to providemore energy dissipation or absorption under greater earthquake forcesthat result in overall building deflections greater than the two inchesrequired by the code. The active element 130 may produce force versusdeflection properties under tension and compression in direction X andopposing senses of shear in direction Y as the building will sway backand forth under earthquake loads producing an oscillating response.

[0067] It shall be understood that the principle of the active element130 may be incorporated into any other type of structural buildingconnector wherein the connector is designed to transmit forces anddissipate/absorb energy. For example, at least one active element may beincorporated into building connectors adapted to attach two portions ofa structure having dissimilar modulus or stiffness, such as a concretewall to a timber framed structure. Alternatively, active element 130 maybe embodied within a corner force-resisting device (not shown) on ashear wall. The corner force-resisting device may be connected to theframing members and the top or bottom plate of the shear wall. Thecorner force-resisting device may be designed so that as forces areimposed at a joint during a loading event, the corner force-resistingdevice transmits force and dissipates/absorbs energy via a defined forceversus deflection property, which may be designed by engineeringanalysis. Depending on the structural location of the application in abuilding or structure, the force versus deflection property may bedesigned for differing absolute and relative levels of stiffness anddissipation. It shall be understood that the building connectors aboveare merely exemplary and should not be considered limiting in anymanner; it is contemplated that other building connectors not listed maybe utilized wherein the connector is designed to transmit forces anddissipate/absorb energy. Such benefits can be obtained at any locationin a structure where relative movement of adjacent parts may occurduring a loading event.

[0068] Referring now to FIGS. 6-9, there are shown computer models andcolor coded results of computer simulations of an exemplary shear wallwith and without the force-resisting device according to the presentinvention undergoing “drift” (deflection) in response to in-plane shearforces as in an earthquake. FIGS. 11-13 show computer models and colorcoded results of computer simulations of the active element 130undergoing deformation due to force application. The analysis resultspresented in FIGS. 6-13 are provided to aid in understanding of thefunction of the invention, and are not to be considered limiting in anyway.

[0069] Referring now to FIG. 6 there is shown an exemplary shear wall200 undergoing drift due to an applied shear force. In each of thedisplays illustrated in FIGS. 6,7, and 9, the drift was restricted totwo inches maximum because two inches of drift is a requirementgenerally accepted by present building codes for an eight-foot highwall, and the deflection is exaggerated for viewing clarity. As shown inFIG. 6, for a solid plywood shear wall, loaded to produce the maximumcode allowable two inches of drift requires a force of approximately9855 pounds to be applied to the shear wall. Additionally, as shown inFIG. 6, the stresses within the solid shear wall sheathing aredistributed smoothly throughout the panel and around the periphery ofthe shear wall.

[0070] Referring now to FIG. 7, there is shown the shear wall 200wherein an opening or discontinuity has been formed therein. The openingformed within the shear wall models a typical window opening of about 30inches×30 inches. As shown in FIG. 7, the center portion 250 adjacent tothe opening 240 deflects greatly due to the applied load. As shown, theshear wall deflects the allowed two inches when only 2807 pounds havebeen applied to the shear wall. Thus the load resisting capacity of theshear wall 200 is reduced by a factor of almost four. Furthermore, asshown in FIG. 7, the opening also produces extreme concentration ofstresses in the corners of the opening as can be evidenced by the redstress pattern indicators 280.

[0071] Referring now to FIG. 8, there is shown the backside of the modelof the shear wall 200. As shown in FIG. 8, the force-resisting device100 of the present invention has been disposed about the periphery ofthe opening 240 formed within the shear wall 200. The force-resistingdevice 100 includes, in this case, four force-resisting members 120 incommunication with the periphery of the opening, wherein each of theforce-resisting members are configured to restore stiffness anddissipation capacity to the shear wall by transferring forces about theperiphery of the opening/discontinuity through controlled deformation ofthe active elements. It shall be understood that the active element maybe configured to deform plastically, elastically, or in any combinationthereof. For example, the active element may initially deformelastically, then as loads increase deform plastically until apredetermined amount of deformation has occurred, then deformelastically again, or the active element may act in a progressiveelastic or plastic manner.

[0072] As shown in FIG. 8, the force-resisting device 100 includes twohorizontal force-resisting members 120 and two vertical force-resistingmembers 120. The force-resisting members 120 each include an activeelement as described in detail above with reference to FIGS. 4A, 4B and5. Further still, the horizontal and/or vertical force-resisting members120 are attached to the plywood panel 12 utilizing fasteners such asscrews, bolts, glues, rivets or similar products disposed through theapertures formed in one end portion of the elongated member(s) 122. Inaddition to being attached on one end to the shear wall, a second end ofthe force-resisting members 120 may be attached to the frame 99, whereinthe frame 99 may be configured as described above. It is furthercontemplated that the force-resisting device 100 in accordance with thepresent invention may comprise a mounting device configured to bedisposed peripherally about an opening. In a preferred embodiment themounting device is formed as a unitary member including at least fourcorner elements and elongated plate members extending therebetween. Themounting device configured to be affixed to the shear wall and toreceive at least one force-resisting member 120 thereon. It is furthercontemplated that the mounting device may be integrally formed with theframe 99 and the force-resisting member 120.

[0073] The force-resisting member including the active element isdesigned to implement the desired known force versus deflectionproperties of the active element. This allows the engineer to select anddesign the proper active element that will provide load sharing across adiscontinuity formed in the shear wall such that the shear wallincluding the force-resisting member performs substantially as if noopening existed in the shear wall. This allows an engineer to “tune” thebuilding such that all of the shear walls behave in a similar manner sothat a force concentration is not created in any portion of the buildingthat could lead to failure of the building.

[0074] As embodied in the present invention and illustrated in thesample computer simulation figures, the active element is configured toundergo deformation, thus carrying the loads from the edge of theplywood panel opening in tension and compression across the activeelement and at the same time absorbing and dissipating energy. Thisparticular modeled design uses steel of the requisite shape andthickness, but it is obvious to one skilled in the art that a wide rangeof materials and configurations in many combinations can be employed toproduce suitable force/deflection properties.

[0075] Referring now to FIG. 9, there is shown the modeled shear wallundergoing drift due to a shear force applied thereto. As shown in FIG.9, to achieve two inches of drift in the shear wall 200 including theforce-resisting device 100 designed for this size opening, in this sizeand configuration shear panel, requires 10,705 lb for force. Comparingthis to FIGS. 6 and 7 it can be seen that the shear wall including theopening 240 and the force-resisting device 100 behaves substantiallylike the shear wall 200 as shown in FIG. 6 with no opening. That is,with the force-resisting device 100 disposed about the periphery of theopening the shear wall including the opening functions in nearly thesame manner as that of a solid shear wall, i.e. it transmitssubstantially similar shear force for a given deflection, and thestresses in the panel are not concentrated and do not result inpremature failure. This can be better understood with reference to thegraph shown in FIG. 10.

[0076] Referring now to FIG. 10 there is shown a graph illustrating theperformance of the shear wall 200 shown in FIGS. 6-9. As shown in thegraph in FIG. 10, the present invention when disposed about an openingformed in a solid shear wall replaces all of the lost stiffness anddissipation capacity of the solid panel. It will be appreciated that theforce versus deflection properties of the invention can be adapted tosuit a wide range of plywood thickness and other shear panel andsheathing material characteristics. The exemplary shear wall modeled inFIGS. 6-9 was modeled to replicate ½″ Douglas fir plywood shear wallsheathing as this is typical of materials used in conventional buildingpractice. Referring now to the graph illustrated in FIG. 10, there isshown three separate load versus deflection characteristic lines. Thefirst line 400 illustrates the load versus deflection characteristics ofthe solid shear wall of FIG. 6, and the second line 500 illustrates theload versus deflection characteristics of the shear wall including a 30inch by 30 inch window opening as illustrated in FIG. 7. As can be seenby the difference between line 400 and line 500 the creation of theopening within the solid shear wall drastically reduces the load bearingcapacity of the shear wall. Referring now to line 600, there is shownthe load versus deflection characteristics of the shear wall includingthe 30×30 inch opening and the force-resisting device 100 in accordancewith the present invention disposed about the periphery of the opening.As shown in the graph of FIG. 10, the present invention restores theshear capacity of the shear wall such that the shear wall including thepresent invention and a 30×30 inch opening formed therein performssubstantially similar to a solid shear wall. Thus, it can be seen thatthe force-resisting device is configured to resist forces and reducestresses and replace stiffness, dissipation, and strength to thestructure such that the structure behaves substantially as if adiscontinuous structural element has not been formed therein.

[0077] Thus it can be seen with reference to FIGS. 4B, 6-10 inaccordance with the present invention there is provided aforce-resisting device for transmitting forces and dissipating andabsorbing energy across a discontinuous structural element of astructure by providing at least one active element having at least afirst end and a second end, the active element having defined forceversus deflection properties and configured to transmit forces anddissipate and absorb energy, wherein the first end of the active elementis configured to be connected to a structure. The force-resisting devicefurther includes at least one frame element disposed about adiscontinuous structural element, wherein the frame element isconfigured to be connected to a second end of the active element, theactive element and the frame element configured to resist forces andreduce stresses and replace stiffness, dissipation, and strength to thestructure.

[0078] Thus it can be seen with reference to FIGS. 4B, 6-10 inaccordance with the present invention there is provided aforce-resisting device for transmitting forces and dissipating andabsorbing energy across a discontinuous structural element of astructure by providing at least one active element having at least afirst end and a second end, the active element having defined forceversus deflection properties and configured to transmit forces anddissipate and absorb energy, wherein the first end of the active elementis configured to be connected to a structure. The force-resisting devicefurther includes at least one frame element connected to a discontinuousstructural element, the frame element is configured to be connected to asecond end of the active element, wherein the active element and theframe element configured to resist forces applied to the structure bytransmitting forces across the discontinuous structural element.

[0079] Additionally, it can be further seen with reference to FIGS. 4B,6-10 in accordance with the present invention there is provided aforce-resisting device for transmitting forces and dissipating andabsorbing energy across a discontinuous structural element of astructure by providing at least one active element having at least afirst end and a second end, the active element having defined forceversus deflection properties and configured to transmit forces anddissipate and absorb energy, wherein the first end of the active elementis configured to be connected to a structure, and at least onereinforcement element, the reinforcement element configured to beconnected to the structure. The force-resisting device further includesat least one frame element disposed about a discontinuous structuralelement, wherein the frame element is configured to be connected to asecond end of the active element, the active element, frame element, andreinforcement element configured to resist forces applied to thestructure by transmitting forces across the discontinuous structuralelement and are further configured to reduce the stresses and replacestiffness, dissipation, and strength to the structure.

[0080] Thus it can be seen with reference to FIGS. 4B, 8, 9, and 10 inaccordance with the present invention that there is provided a methodfor restoring stiffness, energy dissipation capacity, and strength of astructure containing a discontinuous structural element by transmittingforces across the discontinuous structural element, thereby providingload sharing across the discontinuity.

[0081] It will be appreciated by one skilled in the art that the largenumber of calculations required to produce an active element havingaccurately known force versus deflection properties over the entireworking deflection range requires the use of a finite element analysis(FEA) computer program capable of iterative calculations to optimize theperformance of the active element. An example of such a program isANSYS, available from ANSYS, Inc. in Houston, Pa. While it is true thatthe active element can be designed without the use of a computer, toproperly optimize the design would require an overly excessive number ofcalculations and would not be accurate. Therefore, the use of a computermodel in a finite element analysis program is the preferred embodiment.

[0082] Thus it can be seen with regard to FIG. 10 there is provided amethod for selecting a force-resisting device, the force-resistingdevice being configured to transmit loads and to dissipate and absorbenergy by selecting a structural element to be reinforced and selectinga design configuration of a force-resisting device, the force-resistingdevice including at least one active element and selecting a designconfiguration for the active element, then building a computer generatefinite element model of the force-resisting device with at least oneactive element having at least one degree of freedom for transmittingforce and dissipating and absorbing energy, and using the computergenerated finite element model in a finite element analysis program toiterate the design of the active element to produce defined force versusdeflection properties.

[0083] Referring now to FIGS. 11-13 there is illustrated a colorcomputer simulation simulating the forced response of the modeled sampleactive element in accordance with the present invention.

[0084] Referring now to FIG. 11, there is shown a perspective view of asection of an exemplary force-resisting member 120 including the activeelement 130, wherein no force has been applied. The active element 130being defined by three bend points 141, 142, and 143.

[0085] Referring now to FIG. 12, there is shown a sectional view of anexemplary model of a force-resisting member 120 and the active element130 wherein a force has been applied to the force-resisting member 120in the X direction of FIG. 5. As shown in FIG. 12, the active elementundergoes compression resulting in localized elastic and plastic bendingprimarily at the three pre-bent points 141, 142, and 143. The elasticbending effects energy absorption and the plastic bending effects energydissipation, while the geometry and size of the active member providesfor the ability to transmit sufficient load to be effective withoutmaterial failure. Also, to avoid failure, a ductile metal is used forthis case.

[0086] Referring now to FIG. 13, there is illustrated a cross-sectionalview of an exemplary model of a force-resisting member 120 wherein atension force has been applied thereby causing the active element 130 toelongate. By elongating as shown in FIG. 13, the active element issubjected again to localized elastic and plastic bending primarily atthe three pre-bent points 141, 142, and 143, resulting in absorption,dissipation, and load transmitting effects similar to the compressioncase.

[0087] As the active element undergoes compression or tension asillustrated in FIGS. 12-13, the active element behaves in a generalmanner similar to that of the materials of which the shear wall has beenconstructed. That is, the force-resisting device 100 according to thepresent invention is not intended to create a rigid non-yieldingstructure within the shear wall; instead the active element isconfigured to behave in a progressively plastic manner similar to thenatural behavior of the surrounding plywood panel structure and to notcreate an overly stiff portion which would cause the forces to becomeconcentrated therein.

[0088] It will be appreciated that different elements of the inventioncan be manufactured in many ways, either stamped, rolled or bent fromone or more pieces of steel or other material, produced with separatereinforcement elements as in the embodiment shown. It can be made ofnon-metal materials such as engineered plastics and engineeredwood-based products or other engineered materials either alone or incombination with any of the materials listed above in conjunction withsteel and other materials as long as the force versus deflectionproperties are as desired. Use of different materials can also allowreduced heat transmission; it is often desirable to reduce heat lossthrough doors and windows to increase the energy efficiency of thestructure. Use of different materials and combination of materials canalso facilitate installation, by mechanical fasteners, gluing orbonding, interlocking or capture between studs and shear panels or otherelements of the adjacent structure or other fastening means. It shall beappreciated that the force-resisting device in accordance with thepresent invention may be utilized for new building construction or forretrofits by providing a lightweight device that may be easily adaptedfor use within different areas or portions of a structure.

[0089] The implementation of force-resisting devices for different sizeopenings or different discontinuity features in different configurationsof shear walls may be done without changing the design or geometry ofthe active element by using tailored specific lengths of the sameforce-resisting elements on one or more sides of the opening ordiscontinuity.

[0090] The implementation of force-resisting devices for different sizeopenings or different discontinuity features in different configurationsof shear walls may be done by varying the active element design, byusing tailored specific X and Y directional force-resisting behavior onone or more sides of the opening or discontinuity. For example, in somecases, suitable force-resisting devices can be developed using onlyvertical side force-resisting members with no horizontal top and bottomforce-resisting members, provided the Y or vertical direction stiffnessof the remaining vertical members is high in proportion to the X orhorizontal direction stiffness, such that the assembly does not rotateappreciably under load.

[0091] The implementation of force-resisting devices for different sizeopenings or different discontinuity features in different configurationsof shear walls may be augmented by using the frame 99 or frame elementsas an additional active element. For example, the frame itself may bedesigned to dissipate energy by plastic deformation in addition tostiffness and ability to transmit forces. This would in most casesrequire the window or door in the frame to be mounted resiliently toavoid damage.

[0092] Although the present invention has been described in detail withregard to resisting lateral or in-plane forces, as will be appreciatedby one having ordinary skill in the art, the force-resisting deviceaccording to the present invention is also applicable to substantiallyhorizontal perpendicular loads and/or rotational loads which may beapplied to a structure.

[0093] Although the present invention has been described with referenceto specific embodiments, it shall be understood that this should not beconsidered limiting in any manner. Without departing from the spirit andscope of this invention, one of ordinary skill in the art can undertakevarious changes and modifications to the present invention to adapt itto various usages and conditions. As such, these changes andmodifications are intended to be within the full range of equivalence ofthe following claims.

We claim:
 1. A force-resisting device for transmitting forces anddissipating and absorbing energy across a discontinuous structuralelement of a structure, the device comprising: at least one activeelement, the active element having defined force versus deflectionproperties, wherein the active element is configured to provide a loadpath across a discontinuous structural element.
 2. The force-resistingdevice according to claim 1, wherein the active element is configured tobe connected to a structure including the discontinuous structuralelement.
 3. The force-resisting device according to claim 1, whereinsaid load versus deflection property behaves initially elastic and thenchanges to plastic under higher applied loads.
 4. The force-resistingdevice according to claim 1, wherein said load versus deflectionproperty behaves initially elastic, then changes to plastic under higherapplied loads, then changes back to elastic under highest applied loadsto limit deflection.
 5. The force-resisting device according to claim 1,wherein said load versus deflection property behaves initially elastic,then becomes progressively more resistant to load via plasticity underhigher applied loads, thereby dissipating more energy as forces appliedto said active element increase.
 6. The force-resisting device accordingto claim 1, wherein said load versus deflection property behavesinitially elastic, then becomes progressively more resistant to load viacombined elasticity and plasticity under higher applied loads, therebydissipating more energy as forces applied to said active elementincrease.
 7. The force-resisting device of claim 1, wherein theforce-resisting device is a building connector spanning a joint, theconnector configured to transmit force and dissipate and absorb energyvia defined force versus deflection properties.
 8. A force-resistingdevice for transmitting forces and dissipating and absorbing energyacross a discontinuous structural element of a structure, the devicecomprising: at least one active element having at least a first end anda second end, the active element having defined force versus deflectionproperties and configured to transmit force and dissipate and absorbenergy, wherein the first end of the active element is configured to beconnected to a structure; and at least one frame element disposed abouta discontinuous structural element, wherein the frame element isconfigured to be connected to the second end of the active element, theactive element and the frame element are configured to resist forces andreduce stresses and replace stiffness, dissipation, and strength to thestructure.
 9. The force-resisting device according to claim 8, whereinsaid frame element comprises at least one active element.
 10. Theforce-resisting device according to claim 8, wherein said discontinuousstructural element is an opening and the frame elements are configuredto encircle the opening.
 11. A force-resisting device for transmittingforces and dissipating and absorbing energy across a discontinuousstructural element of a structure, the device comprising: at least oneactive element having at least a first end and a second end, the activeelement having defined force versus deflection properties and configuredto transmit force and dissipate and absorb energy, wherein the first endof the active element is configured to be connected to a structure; andat least one frame element configured to be connected to a discontinuousstructural element, said frame element configured to be connected to thesecond end of the active element, wherein the active element and theframe element are configured to resist forces applied to the structureby transmitting forces across the discontinuous structural element. 12.The force-resisting device according to claim 11, wherein said structureconsists of a shear wall.
 13. The force-resisting device according toclaim 11, wherein said discontinuous structural element consists of anopening.
 14. The force-resisting device according to claim 11, whereinsaid frame element comprises at least one active element.
 15. Theforce-resisting device according to claim 11, wherein one active elementis attached to a structural sill plate.
 16. A force-resisting device fortransmitting forces and dissipating and absorbing energy across adiscontinuous structural element of a structure, the device comprising:at least one active element having at least a first end and a secondend, the active element having defined force versus deflectionproperties and configured to transmit force and dissipate and absorbenergy, the first end of the active element configured to be connectedto a structure; at least one reinforcement element, the reinforcementelement configured to be connected to a structure; and at least oneframe element configured to be disposed about a discontinuous structuralelement, wherein the frame element is configured to be connected to thesecond end of the active element, wherein the active element, the frameelement, and the reinforcement element are configured to resist forcesapplied to the structure by transmitting forces across the discontinuousstructural element and are further configured to reduce stresses andreplace stiffness, dissipation, and strength to the structure.
 17. Theforce-resisting device according to claim 16, wherein the structure is ashear wall.
 18. The force-resisting device according to claim 16,wherein the discontinuous structural element is an opening.
 19. A methodof restoring the stiffness, energy dissipation capacity, and strength ofa structure containing a discontinuous structural element, the methodcomprising the step of: transmitting forces across the discontinuousstructural element, thereby providing load sharing across thediscontinuity.
 20. The method according to claim 19 wherein the step oftransmitting further includes attaching at least one active elementdisposed adjacent to the discontinuity formed within the structure. 21.A method for selecting a force-resisting device, the device configuredto transmit loads and to dissipate and absorb energy, the methodcomprising: selecting a structural element to be reinforced; selecting adesign configuration of a force-resisting device containing at least oneactive element; selecting a design configuration for the active element;building a computer generated finite element model of theforce-resisting device with at least one active element, with at leastone degree of freedom for transmitting force and dissipating andabsorbing energy; using the computer generated finite element model in afinite element analysis program to iterate the design of the activeelement to produce defined force versus deflection properties.